The present invention relates generally to hazardous wastes, and, more specifically, to vitrification thereof for long term storage.
The disclosure of U.S. Pat. No. 5,678,237, which provides a method of in-situ vitrification of waste materials in a disposable canister, is incorporated herein by reference. The disposable canister is a module comprising an inner container, an outer container, and insulation therebetween. The outer container serves as the traditional disposal container typically made of steel, which is thermally insulated from an inner container, typically of made of graphite. The inner container serves as a crucible to melt a waste/frit mixture and contain a molten vitrified product.
In the prior patent, concentrated high-level radioactive waste and frit material are added to the inner container, either pre-mixed in a water slurry and added to the inner container, or one at a time with the frit material added first and the slurry of waste added last. The frit material in the traditional process is a granulated, that is, it is in the form of granules, not a solid section of material. Use of a solid section of frit material in a disposable canister and use of chunks of frit is the invention. Use of a solid frit section or solid frit chunks has process benefits in maximizing the fill fraction of solid glass product inside the canister, shortening the required melt period, controlling glass quality, and controlling the time and temperature profile of the process. In variations of the invention, the solid frit section is continuous across the full width of the module, enabling heat to flow unimpeded through the solid glass from the graphite into the interior of the canister.
Accordingly, it is desired to provide an Advanced Vitrification System (AVS) to practice an improved method for modularly processing and vitrifying waste materials, such as nuclear waste, in a disposable canister. A combination and method involving the use of solid frit sections and chunks of frit inside a module is the innovation sought to be protected.